The Role of Pyroptosis in Neuropathic Pain

With a village of mentors and collaborators behind him and the support of The Scientist Track Investigator program at The Hospital for Sick Children and the 2019 IARS Mentored Research Award, Benjamin Steinberg, MD, PhD, FRCPC, was able to build a robust and successful research career in basic science, specifically focused on cell biology. This endpoint truly was jumpstarted when he was awarded the IMRA for his research on “The Role of Pyroptosis in Neuropathic Pain,” which allowed him to conduct the science that most intrigued him, cellular and molecular mechanisms of pain. His 2018 study took unexpected turns along the way, including being impacted by a global pandemic. Initially, the study sought to implicate some of the key molecules and pathways, specifically a molecule called gasdermin D, and delineate how those pathways feed into the inflammatory burden of pain. In that regard, Dr. Steinberg and his collaborators were successful. However, in that investigation, they discovered something surprising, a male-female difference or a sexual dimorphism for this immune modulator. Today, that initial discovery has grown wings. With the help of his research team, they have been able to position this molecule and pathway in a type of neuropathic pain neuritis in an animal model. The research continues to evolve and grow from there. Looking to the horizon, they are now working diligently to corroborate this finding and then phenotype it. Below, Dr. Steinberg shares his research journey, his fascination with how his research has developed over time and his hopes for the future of research and collaboration.

1. What is your current position? How long have you been in this position? What was your role when you were first funded by IARS?

I’m a staff anesthesiologist and a physiologist at the Hospital for Sick Children, Toronto, Canada. I’ve been a staff anesthetist here since 2018-2019. I was promoted or reclassified to scientist as of this summer.

When I was awarded the IMRA, I was actually part of a bona fide informal mentorship program called The Scientist Track Investigator program. So, I successfully matriculated into and then through the program and emerged a scientist one day this past summer. It was a staff position but a scientist track investigator, which is to say, a mentored position.

2. What was the goal of your initial research project? Was it met?

Effectively, it was trying to understand how specific immune modulators and immune pathways are impacting on neuropathic pain and the basic foundation in terms of the method was really around cell biology, understanding really how cells are responding in addition, also animal models. Initially, my strength was really on the cell biology side, and then in terms of animal models. That was something I had started to do in the context of my postdoc, but really was fostered in its fullest with my formal mentor here who is Michael Salter. I had established a mentorship group that included Mike and, in fact, I was really working within his laboratory space. I was really under his umbrella in the sense that I could use his resources. There was no ambiguity, I could reach out to people in his lab for their expertise and advice.

What we ultimately were studying were a bunch of proinflammatory pathways and a bunch of key molecules. At the outset it included the IMRA, but maybe one step a little broader, was looking at these atypical cytokines or typical cytokines, and how they generated pain responses. So, these are acronyms, but they’re all important molecules, like interleukins, interleukin-1 beta being a specific one. High mobility group box one, which is really the more typical side of cytokine and trying to understand how they modulate neural activity and neural responses. Then we brought some of that into animal models and specific types of pain models, technically pain in the context of an animal.

There was a little bit of movement away from the exact initial proposal in so far that science changes a bit, also we hit a pandemic, which is a whole other story. But by and large, as of today, some of the fundamental goals have been achieved. Meaning that we’ve implicated some of these key molecules and pathways, a big one, being a molecule called gasdermin D, a special molecule that starts to polymerize when it’s activated. And it’s actually the conduit through important immune modulators that are released from cells. It also can initiate a cell death pathway called pyroptosis, and delineate how this pathway feeds into the inflammatory burden of pain. It was one of the goals that grew out of this IMRA award and where we are today is basically we have positioned this molecule and pathway in a type of neuropathic pain neuritis in an animal model. The model itself has been changing names, but it was recently published by Mike’s group. They designed it or defined it, or created it, but effectively, if you abrogate the function of this protein, you have enhanced recovery in terms of this nociceptive behavior. And what’s really quite interesting here is that that actually only occurs in males and not females, and so unbeknownst to us, there’s actually a male-female difference or a sexual dimorphism. A large part of our work was just trying to first corroborate the finding and then to phenotype is robust.

That opens up a huge number of questions that we’re trying to figure out, because certainly, I don’t want to quickly jump from rodent models to people. But the truth of the matter is, whether you’re talking about rodents or people, males and females do not behave the same. So sex is a biological variable. It’s a very important one. Other things in clinical patients, obviously like gender, play into this as well. But the notion of sex difference in pain is not actually new. But how and why that occurs is still being explored.

We’ve been able to really untangle how some of this pathway feeds into a nociceptive behavior or pain response. But, we ended up with a really important and big question in front of us which is now trying to understand why there’s a sex difference, and how it is or where it is that males and females diverge. So, that’s the work we are on the cusp of a publication with. We’ve been holding back, and this is in collaboration with Mike in terms of publishing it, just because we really want to get to the real ends or root of all this is, which is how it’s important in males, but less so in females.

In parallel with all that, we’ve been investigating translational approaches in terms of how you would actually target this pathway as a therapeutic.

3. How did your findings impact patient care?

I don’t know if they have directly impacted patient care. That would be a huge overstatement if I said that they did. But the hope is that eventually they will. This is a long journey from basic biomedical research towards bedside. At this point in time, we’ve identified a new pathway in pain, one that hadn’t been really implicated before. We are developing ways of actually therapeutically targeting it and are trialing that at least in our preclinical models. Hopefully, we’ll also unravel some of the mystery around the sexual dimorphism of pain.

The hope is that if we’re successful, obviously with managing or mitigating some of the nociceptive behaviors in animals, that it’s at least worthwhile and provides motivation to start to push this towards clinical patients. Before we impact directly on clinical care, there’s obviously a lot that has to happen. But the importance of this pathway in patients and humans is validating. To that end, we haven’t pushed too hard just yet. But Mike and I, and a few others here, have been trying to figure out how best to at least obtain the appropriate type of patient sample and or patient to see whether there’s a signal for this pathway being activated in our patient populations. That is in the early days yet, but it is unknown how long it will take, and whether it’ll be successful, I really don’t know. I imagine it will be slow going, but, there is at least forward momentum.

4. How did your research impact the field of anesthesiology?

The specialty at large is a very rich history of science and research, both in terms of its own construction and then now, its expansion into important domains of medicine, including pain. Hopefully, it’s going to actually provide new information, or at least an understanding of how pain actually works. I’ve sort of alluded to this notion of sex difference. That’s something that’s really important in clinical practice and yet it’s not something we understand well enough to really go after on a day-to day basis. It’s still sometimes a bit of trial and error. If there are ways of identifying specific characteristics of our patients that would suggest one pathway or another, I would hope that we can lend some insight there, and at least start to tailor specific therapies to specific patients. This might be a bit generous, but I’d like to think that as the specialty sort of expands in science, both the clinical research as well as basic science domains, it further reinforces our capacity as a clinical specialty to conduct impactful and important work. And certainly, that happens on the clinical level. It certainly happens in pain medicine, and our specialty is a real driver of that.

The basic scientists in academic medicine, there really aren’t that many of us, and anesthesiology has actually a pretty strong history of that. But as a larger pool of people, some of whom have also been awarded the IMRA, we are helping to cement that reputation as a specialty of bonafide, successful, important or impactful scientists.

5. How did the award affect your research/professional trajectory?

Hugely, in both ways.

In terms of my research, it really enabled me to conduct the research I wanted to do. As I mentioned, I had some institutional startup funds. I also had some support in terms of infrastructure from Mike Salter, who was my formal mentor in my program. But science is expensive. Research is expensive; basic science is certainly. It allowed me to build my wet lab up. It allowed me to hire highly qualified personnel to help support me in the science I was doing. For all of us in this award are presumably clinician scientists of some form or another, and therefore we have sometimes dueling roles. While I was also managing my clinical time, having someone able to keep pushing the science forward while I was in the lab was really paramount to the success of it. The award was foundational. It was my first award, and it really is a very generous one at that, too. So, it really made it happen for me.

In terms of my professional development, as I was alluding to before, it was perfectly married with the actual program I was in. The award allowed me to do what I wanted to do. And then, in conjunction with the fact that I was in a mentored program, the expectation there was that this takes time. You have to mature and evolve, and eventually grow wings and fly off on your own and everyone was on board from my funding source, which is, of course, your organization, and then the people here.

I was quite lucky the science was and has been successful. And my mentors have been great, both from a scientific and career development perspective. They feed into each other, obviously. But both sides allowed me to still do what I want to do, which is clinical medicine and science.

6. How do you feel about having received the IARS Mentored Research Award?

I’m really fortunate. Before even submitting, I knew 3 people who had been awarded IMRA, all in Toronto. They’re all amazing scientists, people and clinicians, too. I was really quite honored, and in a way surprised, I was awarded. But ultimately extremely thankful. It really put me in a position to succeed.

Thank you for the support. It’s been paramount to my success.

7. What drew you to anesthesiology and to your particular area of research?

First, I’ll just tell you what type of research I do, and then I’ll go back in time and figure out what got me to here.

So, I’m actually a basic scientist, a cell biologist of sorts and a neuroscientist in a way as well. My science and research is basic biomedical research with a translational component to it. And in terms of going back in time and figuring out how I got to where I am today, and what drew me to this current position, I would say that I was actually a scientist before I was an anesthesiologist.

I completed an MD-PhD Program here in Toronto at the University of Toronto, which is really where I started to grow my skills as a basic scientist. Then, I started to complete my medical training, which is really where I got my first exposure to anesthesiology and pain medicine. In terms of what drew me there, it was really the strong emphasis in acute physiology and pathophysiology and the opportunity to manage a patient’s physiologic responses at a particularly vulnerable time, vis-à-vis of clinical disease or surgical trespass. I like the fact that I was able to be a generalist without being an internist or a family doctor, in the sense that I was getting exposure to every type of patient and many different procedures. The scientific training that I had actually received from my graduate work was quite broad in general, and so I had constructed that intentionally and so far, my hope was that after I spent years away from science completing my clinical training, I still had tools that were relevant to conducting science later. I did not anticipate starting back up exactly where I had left off.

As I was going through my clinical training, I was really just trying to find something that spoke to me on the clinical front, and then hoped that I could sort of find the research program that leveraged what I had learned, but, also related to some extent with my clinical practice. I think the former was achieved. The latter is sort of there but more on the pain side, as opposed to the anesthesiology side.

As I was completing my anesthesiology training, let’s say my residency, I took a couple of years off to reinforce some of my scientific training, and that was in the form of a two-year postdoc, half of which was done in the Feinstein Institute for Medical Research in New York, and then half of which was done up here. The purpose there was really to try to integrate a preclinical model of disease and translational elements to my armamentarium terms of research.

When I emerged from all of that, it was the influence of the anesthesiology that stuck. But I was increasingly focused on neuroscience, and that was partly due to my postdoc as well, which was at least partially in a neuroscience lab. I fell on the cellular and molecular mechanisms of pain and started to grow a research plan and program around understanding immune responses, which sort of harkens back to my PhD days of the immune system and inflammatory responses. Engage the nervous system to generate pain phenotypes. In a related way, although it’s not so much the focus of this, but one of the things that really pushed me into the neuroscience, is that as part of my postdoc, which again, is really to learn animal models and translational approaches, was looking at how the nervous system monitors and modulates immune responses. So, I ended up looking at how the immune system is impacting on neural pathways.

Before that, I actually was engaged in a bit of a reciprocal approach which was looking to see how the nervous system is actually engaging and changing immune responses. At the end of all of this, I did one additional year of clinical training to gain expertise in pediatric anesthesia, which is actually what I do now. On the science side, I effectively applied to be part of the Research Institute that’s affiliated with my hospital at the University of Toronto, the Hospital for Sick Kids.

They have a special program here to engage and nurture clinician scientists in this mentored research path, the Scientist Track Investigator Program. It was really nice, because from as institutional perspective, it was a well-supported and tried program. It really mirrors very nicely with what your award is all about. It was a natural confluence that just worked. And then thankfully, I was able to win your support to really push that start forward. My institute provided some small startup funding, but mostly the intellectual capital and mentor support and then your award really allowed me to start to build the program.

I was quite lucky in many respects but more than anything, I’ve learned to put in the work. But really it is the mentorship and support of everyone around you that makes it possible.

8. What is something that someone would be surprised to learn about you?

Before becoming a clinician scientist, which I’ve learned is more than a full-time job, I used to do a lot of rock climbing across the world. I no longer really do it. I guess because of my kids. But my wife and I used to travel across the world to go rock climbing. We have not done that in very long time.

One of our favorite places to climb was actually in Red Rocks in Nevada. It’s amazing and accessible and beautiful.

One of the most incredible places we went was actually in China. These amazing sort of pillars of rock that just emerged from the ground by a flowing river. You’re out in a pretty remote area, which was, in a sense kind of petrifying. But it was spectacular.

9. What do you hope for the future of anesthesia research?

What I would really love to see is actually true medicine at large is communication between clinical and basic biomedical research. It’s really challenging, even for someone like myself. I’m not going to speak for my peers, but others, me, at my institution, we have such a strong clinical research program, pain research program or pediatric clinical medicine research program. And then we have amazing basic scientists. I hope to be part of that group. It’s really hard to unite and tackle larger problems that really require a more holistic approach. We collaborate wonderfully, both locally and then actually, internationally, but what we don’t really have is team-based science or research, larger team enterprises that are tackling, a very specific and fundamental problem for our specialty from every aspect. We really could make impressive gains.

Collaboration has been such a wonderful part of the job. It started in a way with mentorship, but that’s grown and changed to collaboration. It’d be just amazing to expand that even more broadly where we have large scale collaboration across many different types of science, all directed towards solving an important problem.